Method for filling tanks of hydrogen-fueled vehicles

ABSTRACT

A hydrogen refilling station for filling tanks of fuel cell electric vehicles includes a liquid hydrogen tank that feeds liquid hydrogen to an upstream end of a filling circuit that also includes a heat exchanger. The heat exchanger exchanges heat between the liquid hydrogen and heat transfer fluid flows to thereby cool the heat transfer fluid and vaporize the liquid hydrogen to provide a supply of high pressure hydrogen gas for filling hydrogen-fueled vehicle tanks at a downstream end of the circuit. Because the liquid hydrogen is surrounded by the heat transfer fluid inside the heat exchanger, little if any fogging occurs.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/956,064, filed Dec. 31, 2019.

BACKGROUND Field of the Invention

The invention relates to a device for filling pressurized gas tanks.

More particularly, the invention relates to a device for filling thetanks of fuel cell electric vehicles (FCEV), the device comprising aliquefied gas source, a transfer circuit in downstream fluidcommunication with the liquefied gas source and comprising at least onedownstream end adapted and configured to be removably connected to avehicle hydrogen tank to be filled.

Related Art

Hydrogen gas refueling stations using liquid hydrogen sources are known.These known devices make it possible to use refrigeration from theliquid hydrogen to produce pre-cooled pressurized hydrogen gas for rapidfilling without experiencing an excessive increase in the temperature ofthe gas in the tank during filling.

For example, Daney, et al. proposed a conceptual refilling station thatuses a vaporizer for providing ambient temperature, high pressuregaseous hydrogen that is subsequently cooled prior to being fed to thevehicle tank. Daney, et al., “Hydrogen-fueled vehicle fueling station”,Advances in Cryogenic Engineering, vol 41, 1996.

Another such station implemented at an urban bus refilling stationutilizes a vaporizer that transfers heat from the ambient air to thepumped flow of liquid hydrogen to provide a flow of high pressure,gaseous hydrogen to the vehicle tank. Raman, et al. “A rapid fillhydrogen fuel station for fuel cell buses”, 12th World Energy conferenceHydrogen energy Progress 2, pp 1629-1642.

At atmospheric pressure, the boiling point of hydrogen is −252.8° C.Because the station disclosed in Raman, et al. uses a vaporizer thatexchanges heat between the liquid hydrogen and ambient air, the skintemperature of the ambient air vaporizer is exceedingly low. As aresult, water vapor from the ambient air condenses and freezes onsurfaces of the ambient air vaporizer. Also air around the ambient airvaporizer condenses and drips on the equipment below. This creates arisk for the equipment below. Equipment may become thermally embrittled,especially equipment that is made of carbon steel, and plates may crack,structural beams may fail, and pipes may burst. Since oxygen willcondense at a higher temperature than nitrogen, an oxygen enrichedatmosphere may be created. There are of course many known riskspresented by an oxygen-rich atmosphere. Furthermore, the condensing airexacerbates the cryogenic cloud around the equipment.

When the depth of the frozen water on the surface of the ambient airvaporizer reaches an unsatisfactory depth, thereby decreasing effectiveheat transfer, or even results in bridging in between adjacent vanes ofthe ambient air vaporizer, such a vaporizer must be defrosted beforefurther use is continued. To solve this problem, two ambient airvaporizers may be used in alternating fashion so that while one is beingdefrosted, the other is used to vaporize the liquid hydrogen. While thissolves the problem, it can unsatisfactorily increase capital costsbecause of the necessity of having two ambient air vaporizers for eachfilling circuit. For hydrogen filling stations located in areas wherethe real estate is costly and/or for hydrogen filling stationsco-located at a retail gasoline station where the space for the stationis leased from the retail gasoline station, capital expenses are alsoincreased because the necessity of having two vaporizers doubles thefootprint or space taken up by the liquid vaporization portion of thestation.

Because the skin temperature of the ambient air vaporizer is so low,water vapour in the ambient air also condenses in regions surroundingthe vaporizer, creating fogging conditions.

While fogging can be a nuisance for refilling stations isolated from thepublic, such as in an industrial area ordinarily far from consumers,fogging is a much more serious problem for more conspicuous refillingstations, such as at retail hydrogen refilling stations, opendemonstration refilling stations, and hydrogen filling stationsco-located with retail gasoline stations. This is because members of thepublic will view the fogging emanating from a hydrogen refilling stationand incorrectly conclude that either a dangerous leak of hydrogen hasoccurred at the station or even that a fire has broken out at thestation. Erroneous reports of disastrous leaks or dangerous fires toemergency responders will therefore require that the station besubjected to an emergency stop followed by a thorough safety assessmentbefore the station may be declared safe for operation. For this reason,the use of ambient vaporizers can seriously impede the development ofhydrogen refilling stations sourced by on-site tanks of liquid hydrogenand located in conspicuous areas viewable by the public.

SUMMARY OF THE INVENTION

An aim of the invention is to overcome all or some of the prior artdisadvantages stated above.

There is disclosed a hydrogen refilling station, comprising a liquidhydrogen source adapted and configured to store liquid hydrogen, afilling circuit, and a heat exchange fluid circuit. The filling circuithas an upstream end in downstream fluid communication with the liquidhydrogen source to allow a flow of liquid hydrogen from the source intothe filling circuit, a downstream end adapted and configured to beremovably connected with a FCEV tank for filling of the tank with, and afirst heat exchanger disposed between the upstream and downstream endsof the filling circuit. The heat transfer circuit comprises, in floworder, an upstream end in downstream flow communication with the firstheat exchanger, a second heat exchanger, a heat transfer fluid pump, anda downstream end in upstream flow communication with the first heatexchanger, the heat transfer fluid pump being adapted and configured toreceive the heat transfer fluid from the second heat exchanger anddirect it to the first heat exchanger. The second heat exchanger isadapted and configured to warm cooled heat transfer fluid received fromthe first heat exchanger. The first heat exchanger is adapted andconfigured to exchange heat between the heat transfer fluid flowingthrough the heat transfer circuit and liquid hydrogen in the fillingcircuit so as to cool the heat transfer fluid and vaporize the liquidhydrogen to provide the pressurized, gaseous hydrogen for filling thetank, the flow of liquid hydrogen inside the first heat exchanger beingsurrounded by the flow of the heat transfer fluid.

There is also disclosed a hydrogen refilling station, comprising aliquid hydrogen source adapted and configured to store liquid hydrogen,first and second filling circuits, a heat transfer fluid reservoir, andfirst and second heat exchange fluid circuits, wherein: the firstfilling circuit has an upstream end in downstream fluid communicationwith the liquid hydrogen source to allow a flow of liquid hydrogen fromthe source into the first filling circuit, a downstream end adapted andconfigured to be removably connected with a hydrogen-fueled vehicle tankfor filling of the tank with, and a first heat exchanger disposedbetween the upstream and downstream ends of the first filling circuit;the second filling circuit has an upstream end in downstream fluidcommunication with the liquid hydrogen source to allow a flow of liquidhydrogen from the source into the second filling circuit, a downstreamend adapted and configured to be removably connected with ahydrogen-fueled vehicle tank for filling of the tank with, and a firstheat exchanger disposed between the upstream and downstream ends of thesecond filling circuit; the first heat transfer circuit comprises, inflow order, an upstream end in downstream flow communication with thefirst heat exchanger of the first filling circuit, a second heatexchanger, a heat transfer fluid pump, and a downstream end in upstreamflow communication with the first heat exchanger of the first fillingcircuit, the heat transfer fluid pump of the first heat transfer circuitbeing adapted and configured to receive the heat transfer fluid from thesecond heat exchanger of the first heat transfer circuit and direct itto the first heat exchanger of the first filling circuit; the secondheat transfer circuit comprises, in flow order, an upstream end indownstream flow communication with the first heat exchanger of thesecond filling circuit, a second heat exchanger, a heat transfer fluidpump, and a downstream end in upstream flow communication with the firstheat exchanger of the second filling circuit, the heat transfer fluidpump of the second heat transfer circuit being adapted and configured toreceive the heat transfer fluid from the second heat exchanger of thesecond heat transfer circuit and direct it to the first heat exchangerof the second filling circuit; the second heat exchanger of the firstheat transfer circuit is adapted and configured to warm cooled heattransfer fluid received from the first heat exchanger of the first heattransfer circuit; and the second heat exchanger of the second heattransfer circuit is adapted and configured to warm cooled heat transferfluid received from the first heat exchanger of the second heat transfercircuit; the heat transfer fluid reservoir is in fluid communicationbetween the second heat exchanger and heat transfer fluid pump of thefirst heat transfer circuit and is in fluid communication between thesecond heat exchanger and heat transfer fluid pump of the second heattransfer circuit; the first heat exchanger of the first filling circuitis adapted and configured to exchange heat between the heat transferfluid flowing through the first heat transfer circuit and liquidhydrogen in the first filling circuit so as to cool the heat transferfluid and vaporize the liquid hydrogen to provide the pressurized,gaseous hydrogen for filling a tank of a hydrogen-fueled vehicle, theflow of liquid hydrogen inside the first heat exchanger of the firstfilling circuit being surrounded by the flow of the heat transfer fluid;and the first heat exchanger of the second filling circuit is adaptedand configured to exchange heat between the heat transfer fluid flowingthrough the second heat transfer circuit and liquid hydrogen in thesecond filling circuit so as to cool the heat transfer fluid andvaporize the liquid hydrogen to provide the pressurized, gaseoushydrogen for filling a tank of a hydrogen-fueled vehicle, the flow ofliquid hydrogen inside the first heat exchanger of the second fillingcircuit being surrounded by the flow of the heat transfer fluid.

There is also disclosed a method of filling a hydrogen-fueled vehicletank with pressurized hydrogen, comprising the following steps. Liquidhydrogen is fed from a source of liquid hydrogen a filling circuit whosedownstream end is removably connected to a tank of a hydrogen-fueledvehicle, the filling circuit having a first heat exchanger is disposedtherein, the first heat exchanger having a liquid hydrogen inlet, agaseous hydrogen outlet, a heat transfer fluid inlet, and a heattransfer fluid outlet. A heat transfer fluid is pumped with a heattransfer pump through a heat transfer circuit looping from and to thefirst heat exchanger, the heat transfer circuit comprising, in floworder from the heat transfer fluid outlet to the heat transfer fluidinlet, a second heat exchanger and the heat transfer fluid pump. Heat isexchanged, with the first heat exchanger, between the heat transferfluid flowing through the heat transfer fluid circuit and the liquidhydrogen fed to the filling circuit from the source, thereby vaporizingthe fed liquid hydrogen and cooling the heat transfer fluid, wherein thefed liquid hydrogen inside the first heat exchanger is surrounded by theheat transfer fluid. The cooled heat transfer fluid received from thefirst heat exchanger is heated with the second heat exchanger. A tank ofa hydrogen-fueled vehicle is filled with pressurized, gaseous hydrogenfrom the downstream end of the filling circuit.

The station or method may include one or more of the following aspects:

-   -   liquid hydrogen is pumped with a liquid hydrogen pump from the        source into the filling circuit.    -   a pressure of the pressurized, gaseous hydrogen in the filling        circuit downstream of the first heat exchanger is measured with        a pressure sensor; and a pressure of the pressurized, gaseous        hydrogen is controlled with a pressure control valve based upon        the pressure of the pressurized, gaseous hydrogen measured by        the pressure sensor.    -   a liquid hydrogen pump is in downstream flow communication with        the liquid hydrogen source and upstream flow communication with        the first heat exchanger and is adapted and configured to        increase a pressure of the flow of liquid hydrogen from the        liquid hydrogen source and to direct the pressurized flow of        liquid hydrogen towards the first heat exchanger.    -   the filling circuit further comprises a pressure control valve        and a pressure sensor downstream of the first exchanger and the        pressure control valve is adapted and configured to control a        pressure of the pressurized, gaseous hydrogen for filling the        tank based upon a pressure of the pressurized, gaseous hydrogen        measured by the pressure sensor.    -   the heat transfer circuit further comprises a primary line, a        bypass line, a three-way flow control valve, a temperature        sensor, and a downstream line in flow communication between the        three-way flow control valve and the heat transfer fluid pump;        the primary line extends in flow communication between the first        heat exchanger and the three-way flow control valve; the bypass        line branches off of the primary line and is in upstream flow        communication with the three-way flow control valve; the second        heat exchanger is disposed in the primary line; the three-way        flow control valve controls flows of warmed heat transfer fluid        from the primary line and non-warmed heat transfer fluid from        the bypass line, combines the flow of the warmed heat transfer        fluid from the primary line and the flow of the non-warmed heat        transfer fluid from the bypass line, and directs the combined        flow of heat transfer fluid to the heat transfer pump; the        temperature sensor is disposed in the heat transfer circuit in        between the three-way flow control valve and the first heat        exchanger; and the three-way control valve controls a        temperature of the heat transfer fluid in between the three-way        control valve and the first heat exchanger by adjusting a ratio        of the flow rate of the warmed heat transfer fluid to the flow        rate of the non-warmed heat transfer fluid in the combined flow        of heat transfer fluid.    -   the heat transfer fluid circuit further comprises a blower that        is adapted and configured to blow ambient air at the second heat        exchanger so as to warm the heat transfer fluid with the heat of        the blown ambient air.    -   the second heat exchanger is an electric heater adapted and        configured to warm the heat transfer fluid.    -   the station includes two or more buffer containers, a leg        branching off of the filling circuit downstream of the first        heat exchanger that is adapted and configured to direct the        pressurized, gaseous hydrogen from the first heat exchanger to        the two or more buffer containers, a set of valves, and a        pressure control valve, the set of valves being adapted and        configured to allow the pressurized, gaseous hydrogen to flow        through the leg and into one of the buffer containers but not        into other of the buffer containers and allow the pressurized,        gaseous hydrogen to flow from one of the buffer containers        through the leg and to the downstream end of the filling        circuit, the pressure control valve being adapted and configured        to control a pressure of the pressurized, gaseous hydrogen        flowing out of the downstream end of the filling circuit based        upon a pressure sensed by a pressure sensor disposed in the        filling circuit between the leg and the downstream end of the        filling circuit.    -   the filling circuit further comprises a primary line in fluid        communication between the upstream and downstream ends of the        filling circuit, a bypass line that branches off from the        primary line and recombines with the primary line downstream of        the first heat exchanger, a flow control valve disposed in the        primary line, a flow control valve disposed in the bypass line,        and a temperature sensor disposed in the filling circuit        downstream of a point where the bypass line recombines with the        primary line and upstream of the downstream end of the filling        circuit, the first heat exchanger being disposed in the primary        line, the flow control valve disposed in the primary line being        adapted and configured to control a flow of vaporized hydrogen        flowing through the primary line, the flow control valve        disposed in the bypass lines being adapted and configured to        control a flow of liquid hydrogen flowing through the bypass        line, the flow control valves controlling the flows of vaporized        hydrogen and liquid hydrogen to in turn control a temperature of        the pressurized, gaseous hydrogen for filling the tank that is        based upon a temperature sensed by the temperature sensor.    -   the heat transfer circuit further comprises a heat transfer        reservoir in fluid communication between the second heat        exchanger and the heat transfer pump, the heat transfer        reservoir being adapted and configured to contain a volume of        the heat transfer fluid.    -   the station further comprises: a first liquid hydrogen pump in        downstream flow communication with the liquid hydrogen source        and upstream flow communication with the first heat exchanger of        the first filling circuit that is adapted and configured to        increase a pressure of the flow of liquid hydrogen from the        liquid hydrogen source and direct the pressurized flow of liquid        hydrogen towards the first heat exchanger of the first filling        circuit; and a second liquid hydrogen pump in downstream flow        communication with the liquid hydrogen source and upstream flow        communication with the first heat exchanger of the second        filling circuit that is adapted and configured to increase a        pressure of the flow of liquid hydrogen from the liquid hydrogen        source and direct the pressurized flow of liquid hydrogen        towards the first heat exchanger of the second filling circuit.    -   each of the filling circuits further comprises a pressure        control valve and a pressure sensor downstream of the associated        first exchanger and the pressure control valve is adapted and        configured to control a pressure of the pressurized, gaseous        hydrogen for filling a tank of a hydrogen-fueled vehicle based        upon a pressure of the pressurized, gaseous hydrogen measured by        the pressure sensor.    -   each of the heat transfer circuit further comprises a primary        line, a bypass line, a three-way flow control valve, a        temperature sensor, and a downstream line in flow communication        between the three-way flow control valve and the heat transfer        fluid pump; each primary line extends in flow communication        between the associated first heat exchanger and the associated        three-way flow control valve; each bypass line branches off of        the associated primary line and is in upstream flow        communication with the associated three-way flow control valve;        each second heat exchanger is disposed in the associated primary        line; each three-way flow control valve controls flows of warmed        heat transfer fluid from the associated primary line and        non-warmed heat transfer fluid from the associated bypass line,        combines the flow of the warmed heat transfer fluid from the        associated primary line and the flow of the non-warmed heat        transfer fluid from the associated bypass line, and directs the        combined flow of heat transfer fluid to the associated heat        transfer pump; each temperature sensor is disposed in the        associated heat transfer circuit in between the associated        three-way flow control valve and the associated first heat        exchanger; and each three-way control valve controls a        temperature of the heat transfer fluid in between it and the        associated first heat exchanger by adjusting a ratio of the flow        rate of the warmed heat transfer fluid to the flow rate of the        non-warmed heat transfer fluid in the combined flow of heat        transfer fluid.    -   each heat transfer fluid circuit further comprises a blower that        is adapted and configured to blow ambient air at the associated        second heat exchanger so as to warm the heat transfer fluid with        the heat of the blown ambient air.    -   each second heat exchanger is an electric heater adapted and        configured to warm the heat transfer fluid.    -   each filling circuit further comprises: a primary line in fluid        communication between its upstream and downstream ends; a bypass        line that branches off from the associated primary line and        recombines with the associated primary line downstream of the        associated first heat exchanger; a flow control valve disposed        in the associated primary line; a flow control valve disposed in        the associated bypass line; and a temperature sensor disposed        downstream of a point where the associated bypass line        recombines with the associated primary line and upstream of the        associated downstream end thereof, wherein: the associated first        heat exchanger is disposed in the associated primary line; the        flow control valve disposed in the associated primary line being        adapted and configured to control a flow of vaporized hydrogen        flowing through the associated primary line; the flow control        valve disposed in the associated bypass line being adapted and        configured to control a flow of liquid hydrogen flowing through        the associated bypass line, the flow control valves controlling        the flows of vaporized hydrogen and liquid hydrogen to in turn        control a temperature of the pressurized, gaseous hydrogen for        filling a tank of a hydrogen-fueled vehicle that is based upon a        temperature sensed by the temperature sensor.    -   the downstream end comprises at least two nozzles each of which        is adapted and configured to be removably connected with a        hydrogen-fueled vehicle tank for filling of the tank with.

BRIEF DESCRIPTION OF THE FIGURES

Other characteristic features and advantages will emerge upon readingthe following description, with reference to the figures in which:

FIG. 1 is a schematic view of an embodiment of the inventive station andmethod of the invention.

FIG. 2 is a schematic view of a variant of the station and method ofFIG. 1.

FIG. 3 is a schematic view of a variant of the station and method ofFIG. 1.

FIG. 4 is a schematic view of a combination of features of the stationsand methods of FIGS. 2 and 3.

FIG. 5 is a schematic view of a variant of the station and method ofFIG. 4.

FIG. 6 is a schematic view of a variant of the station and method ofFIG. 5.

LEGEND

-   liquid hydrogen source 1-   filling circuit 2-   first heat exchanger 3-   heat transfer fluid circuit 4-   pressure control valve 5-   vehicle 6-   optional chiller 7-   pressure sensor 9-   shut-off valve 10-   temperature sensor 11-   second heat exchanger 15-   heat transfer fluid circuit primary line 16-   heat transfer fluid circuit bypass line 17-   blower 19-   three-way control valve 21-   heat transfer fluid reservoir 23-   heat transfer fluid pump 25-   temperature sensor 27-   temperature sensor 29-   liquid hydrogen pump 31-   valve 33-   buffer container 35-   leg 37-   filling circuit primary line 39-   filling circuit bypass line 41-   combination point 42-   temperature control valve 43-   temperature control valve 45-   shut-off valve 46-   shut-off valve 48-   shut-off valve 50

DETAILED DESCRIPTION OF THE INVENTION

As best shown in FIG. 1, liquid hydrogen from a liquid hydrogen source 1is fed to a filling circuit 2, via an upstream end thereof; thatincludes a first heat exchanger 3, a pressure control valve 5, a secondheat exchanger 15. The downstream end of the filling circuit 2 isremovably connected to a tank of a hydrogen fuel cell electric vehicle(FCEV) 6. Heat transfer fluid flows in a heat transfer fluid circuit 4that includes a heat transfer fluid pump 25, a temperature sensor 27,and a liquid hydrogen pump 31.

The source optionally includes a pressure building circuit for buildingpressure in a headspace of the source by controlling amounts of liquidhydrogen from the source to exit the source and enter into a line inthermal connection with ambient air, using a flow control valve. Theliquid hydrogen vaporizes in the line and is directed into theheadspace. A pressure sensor measures a pressure inside the headspace. Acontroller is used to actuate the flow control valve based upon themeasured headspace pressure so as to reach a desired pressure in theheadspace.

The liquid hydrogen pump 31 is used to feed and pressurize the liquidhydrogen from the source and into the filling circuit. The use of aliquid hydrogen pump 31 allows the liquid hydrogen to be pumped to thesupercritical pressures that are desired for high pressure fills of thetanks of the hydrogen-fueled vehicle 6. For example, liquid hydrogenstored in the source 1 at a pressure of around 50 bar may be easilypumped to a pressure of 900 bar or even higher. The properties andfeatures of the particular liquid hydrogen pump 31 employed areordinarily driven by the desired maximum pressure to be provided to thetank of the FCEV 6 and the desired filling capacity of the refillingstation. Preferably, each liquid hydrogen pump 31 is characterized bythe following operating conditions: a net positive suction head of 2-5psi, a nominal flow capacity of 45 kg/h, a 100 psi liquid hydrogensuction pressure, and a maximum discharge pressure of about 15,000 psi.

Liquid hydrogen fed into the filling circuit 2 from the source 1 isvaporized at the first heat exchanger 3 to provide pressurized, gaseoushydrogen for filling the tank of the FCEV 6. The first heat exchanger 3exchanges heat between the heat transfer fluid flowing in the heattransfer fluid circuit 4 and the liquid hydrogen flowing in the fillingcircuit 2, thereby vaporizing the liquid hydrogen (yielding coldhydrogen in supercritical fluid state) and cooling the heat transferfluid. The vaporized liquid hydrogen constitutes the pressurized,gaseous hydrogen used to filling the tank of the hydrogen-fueled vehicle6. Either a driver/customer of the FCEV 6 or an operator of therefilling station may access the nozzle (at the downstream end of thefilling circuit 2) conveniently located at an interface typically foundat a standard gasoline station (i.e., a gas pump) which includes adisplay of the price of the hydrogen, the quantity of hydrogendelivered, and a start/stop button.

The cooled heat transfer fluid is warmed at the second heat exchanger 15and pumped back to the first heat exchanger 3 using the heat transferfluid pump 25. The second heat exchanger 15 may be an ambient airvaporizer in which the cooled heat transfer fluid is warmed with theheat from the ambient air blown onto the ambient air vaporizer with theblower. Optionally, the second heat exchanger may be an electric heater.

While any known heat transfer fluid that is in the liquid phase atnominal pressures down to at least −135° C., a non-limiting andparticularly suitable example of one is available from Eastman under thebrand name Therminol VLT®. Therminol VLT® is a mixture ofmethylcyclohexane and trimethylpentane and has a reported liquid heatcapacity ranging from 1.29 kJ/(kg·K) at −135° C. to 2.04 kJ/(kg·K) at40° C.

The temperature of the heat transfer fluid may be controlled as follows.A controller (not illustrated) controls the speed of the heat transferfluid pump 25 (such as by increasing or decreasing the speed of avariable frequency drive of the pump 25) based upon the temperature ofthe heat transfer fluid sensed by temperature sensor 29. If thetemperature of the heat transfer fluid just upstream of the first heatexchanger 3 is unsatisfactorily high, it will impair the ability of theheat transfer fluid to warm the liquid hydrogen flowing through thefirst heat exchanger 3. On the other hand, if the temperature of theheat transfer fluid is too low, it may become too viscous or evenfrozen. The controller is typically a computer or programmable logiccontroller. More specifically, the temperature of the heat transferfluid downstream of the first heat exchanger may be controlled within atemperature range or according to a temperature set point.

Inside the first exchanger 3, the flow of liquid hydrogen is surroundedby the flow of heat transfer fluid. This prevents an exterior skintemperature of the first exchanger 3 from reaching the exceedingly coldtemperatures experienced by ambient air vaporizers of conventionalliquid hydrogen-source hydrogen filling stations. Thus; condensation ofwater vapor upon the first heat exchanger 3 and consequent frosting (andthe associated problems of defrosting in the prior art as discussedabove) is avoided. Also, condensation of water vapor in regionssurrounding the first exchanger 3 (and the associated problems offogging in the prior art as discussed above) is avoided. Typically, theconfiguration of the first heat exchanger 3 is tube-in-tube where theliquid hydrogen flows through the inner tube and the heat transfer fluidflows in the outer tube. For pressures of about 900 bar, a tube in tubeheat exchanger is less complex and less costly than a shell and tubeheat exchanger. The first heat exchanger may instead be a shell and tubeheat exchanger in which the tube fluid is liquid hydrogen and the shellfluid is the heat transfer fluid. Types of heat exchangers other thanthe pipe-in-pipe or shell and tube configurations may be used for thefirst heat exchanger 3 may be used with the invention so long as theliquid hydrogen is surrounded by heat transfer fluid and/or the skintemperature of an exterior of the first heat exchanger 3 does not reachthe exceedingly low temperatures of conventional ambient air vaporizersand fogging and frosting are avoided. Portions of the filling circuitupstream of the first heat exchanger may be vacuum-jacketed to preventthe frosting and fogging problems.

The pressure of the hydrogen used to fill the tank of the FCEV 6 may becontrolled with a pressure control valve 5. While the particular mannerin which the tank is filled is not limited, typically the tank is filledaccording to a standard filling scheme such as the Society of AutomotiveEngineers (SAE) standard J2601. The pressure control valve 5

As best illustrated in FIG. 2, the hydrogen filling station may alsoinclude one or more buffer containers 35 for containing high pressurehydrogen, downstream of the first heat exchanger. Each of the buffercontainers may be provided with a pressure building circuit in order tomaintain a desired pressure within. The vaporized hydrogen is fed to thebuffer containers via a leg 37 appending from the filling circuit 2. Thepressure control valve 5 may be used to fill the tank of thehydrogen-fueled vehicle using a filling algorithm as discussed above. Asin FIG. 1, the liquid hydrogen is pumped to high pressure by liquidhydrogen pump 31 and heated by the heat transfer fluid at the first heatexchanger 3. Shut-off valve 48 is closed, shut-off valve 46 is open, andone or more of the shut-off valves 50 are open. Instead of being fed tothe FCEV directly, the cold supercritical hydrogen is used to fill onemore of the buffer containers 35. Optionally, one of the buffercontainers 35 is at medium pressure while another is at high pressure.By selective opening or closing of the shut-off valves 50, the buffercontainer 35 at high pressure may be filled first and the buffercontainer 35 at medium pressure filled second. Unless one or more of thebuffer containers 35 is at an undesirably low pressure, the liquidhydrogen pump 31 need not be continuously run. If the buffer containers35 are full, the tank of the FCEV 6 may be filled with hydrogen storedin the buffer containers 35 in a cascade fill in which the buffercontainer 35 at medium pressure is pressure-equalized with the tank ofthe FCEV 6 and subsequently the buffer container 35 at high pressure ispressure-equalized with the tank as is known in the art.

As best shown in FIG. 3, the second heat exchanger 15 may be an ambientair vaporizer, the filling circuit 2 may also include an optionalchiller 7 and pressure and temperature sensors 9, 11, and the heattransfer fluid circuit 4 may include a heat transfer fluid reservoir 23and a temperature sensor 27. The tank of an FCEV may be filled using thepressure control valve 5 as described above, based upon the pressure andtemperature sensed by pressure and temperature sensors 9, 11, The heattransfer fluid circuit 4 is provided with a primary line 16 in which thesecond heat exchanger 15 is disposed. The cooled heat transfer fluid iswarmed with the heat from the ambient air blown onto the second heatexchanger 15 with a blower 19. Optionally, there is also a bypass line17 that branches off of the primary line 16 such that a portion of thecooled heat transfer fluid is not warmed at the second heat exchanger15. In such an optional case, the warmed heat transfer fluid in theprimary line 16 is combined with the non-warmed heat transfer fluid inthe bypass line 17 using a three-way control valve 21. Because theambient air temperature blown by the blower 19 will vary with the timeof year, the three-way control valve 21 may be controlled according to acontrol scheme which varies by the season. For example, during thewinter in the northern hemisphere, the entirety of the flow of the heattransfer fluid may be fed through the primary line 16 and be heated atthe second heat exchanger 15, whereas during the summer, a portion orall of the flow of the heat transfer fluid may be fed through the bypassline 17 in order to yield a colder heat transfer fluid for storage in aheat transfer fluid reservoir 23. This is helpful during especially hotweather in the summer when heat leaks impair the ability to maintain theheat transfer fluid below a maximum predetermined temperature.

The temperature of the combined flow of heat transfer fluid from thethree-way control valve 21 may alternatively be controlled in thefollowing manner, A controller (which may be the same as or differentfrom the controller used to control the temperature of the heat transferfluid downstream of the first heat exchanger 3) controls actuation ofthe three-way control valve to achieve a ratio of the flow of warmedheat transfer fluid in the primary line and non-warmed heat transferfluid in the bypass line based upon the temperature measured by thetemperature sensor of the heat transfer circuit.

The pressure and temperature sensors 9, 11 may be used to input apressure and temperature of the hydrogen delivered to the FCEV tank asvariables into a filling algorithm as described above. In particular,the filing algorithm is in compliance with SAE standard J2601.

As best in shown in FIG. 4, the features of the embodiments of FIGS. 2and 3 may be combined.

As best illustrated in FIG. 5, the filling circuit includes a primaryline 39 and a bypass line 41 that branches off of the primary line. Theportion of the liquid hydrogen fed to the primary line 39 is vaporizedat the first heat exchanger 3 while the portion of the liquid hydrogenfed to the bypass line 41 is not. The two flows of hydrogen are combinedat a point 42 downstream of the first heat exchanger 3 to provide thepressurized, gaseous hydrogen. The temperature of the pressurized,gaseous hydrogen may be controlled by controlling the flows of liquidhydrogen into the primary and bypass lines 39, 41 with temperaturecontrol valves 43, 45. The temperature control valves 43, 45 may becontrolled with a controller (not shown but examples include a computeror a programmable logic controller which may be the same as or differentfrom controller(s) that controls operation of the three-way controlvalve 21 and/or the liquid hydrogen pump variable frequency drive) basedupon the temperature measured by the temperature sensor 11. The skilledartisan will recognize that, when the temperature sensed by thetemperature sensor is too low (high), the flow of liquid hydrogen to theprimary line 39 may be increased (decreased) and the flow of liquidhydrogen to the bypass line 41 may be decreased (increased) by acorresponding amount. Thus, control of the temperature of thepressurized, gaseous hydrogen may be performed without the optionalchiller 7 or the optional chiller 7 may provide supplementalrefrigeration only. In this embodiment, the flow of gaseous hydrogen tothe FCEV tank is controlled by pressure control valve 5, optionallybased upon the pressure and temperature sensed by the pressure andtemperature sensors 9, 11 as explained above.

If the FCEV tank is not being filled with hydrogen from the buffercontainers 35, shut-off valves 50 are closed and the two flows ofhydrogen are combined at a point 42 downstream of the first heatexchanger 3 to provide the pressurized, gaseous hydrogen for filling theFCEV tank. If one of the buffer containers 35 is being used to fill theFCEV tank, one of the shut-off valves 50 is closed, one of the shut-offvalves 50 is open and a flow of hydrogen from one of the buffercontainers 35 is combined with a flow of liquid hydrogen from the bypassline 41 at the point 42 downstream of the first heat exchanger 3. Duringsuch a fill, the pump 31 may keep running or optionally it may be turnedoff. Regardless of whether the vaporized hydrogen is obtained directlyfrom the primary line 39 or from one of the buffer containers 35, thetemperature of the pressurized, gaseous hydrogen may be controlled bycontrolling the flows of liquid hydrogen in the primary and bypass lineswith temperature control valves 43, 45. The temperature control valves43, 45 may be controlled with a controller (not shown but examplesinclude a computer or a programmable logic controller which may be thesame as or different from controller 29) based upon the temperaturemeasured by the temperature sensor. The skilled artisan will recognizethat, when the temperature sensed by the temperature sensor is too low(high), the flow of liquid hydrogen to the primary line 39 may beincreased (decreased) and the flow of liquid hydrogen to the bypass line41 may be decreased (increased) by a corresponding amount. Thus, controlof the temperature of the pressurized, gaseous hydrogen may be performedwithout the optional chiller or the optional chiller may providesupplemental refrigeration only. In this embodiment, the flow of gaseoushydrogen to the FCEV tank is controlled by pressure control valve basedupon the pressure sensed by the pressure sensor.

In a variant of the embodiment of FIG. 5 and as best illustrated in FIG.6, the station may have two filling circuits 4′, 4″. This allows theliquid hydrogen from the source 1 to be supplied to either of the liquidhydrogen pumps 31 and compressed liquid hydrogen may be supplied toeither of the two filling circuits 4′, 4′ from either liquid hydrogenpump. Although not illustrated, a single set of buffer containers 35 maybe shared in common with each of the filling circuits 4′, 4″ allows thesize of the buffer containers to be optimized, thereby decreasingcapital costs.

In each of the foregoing embodiments, it should be noted that thedownstream end may be equipped with at least two nozzles. Each of thenozzles is adapted and configured to be removably connected with thetank of a FCEV for filling of the tank with. While any knownconfiguration of nozzle may be used, typically the nozzle is part of ahydrogen dispenser available from Tatsuno Corporation for use in retailhydrogen refilling stations.

Regardless of the particular embodiment, while the refilling station maybe located anywhere FCEV tanks need refilling, it is of particularusefulness when located at a retail fuel station fitted with hydrogendispensers for use by drivers of FCEVs who do not necessarily have anytraining in the handling and dispensing of high pressure hydrogen. In apreferred filling sequence, after the nozzle is connected in gas-tightfashion with the FCEV tank, gaseous hydrogen is first fed from thelowest pressure buffer container (that is at a pressure higher than thatof the hydrogen in the tank) and into the tank in order to decrease theimpact of the Joule-Thomson effect. The particular manner in which thefilling is performed is dictated by the filling algorithm, such as onecompliant with the SAE J2601 standard. Control of the pressure of thegaseous hydrogen from the nozzle is done with a pressure control valvebased upon the pressure of the gaseous hydrogen by a pressure sensor inthe nozzle or in the tank. When the lower pressure buffer container andthe tank are essentially pressure-equalized, gaseous hydrogen is insteaddispensed from a higher pressure buffer container and into the tank.This is continued until completion of the fill, according to thealgorithm, is indicated. Before another FCEV tank is filled, the liquidhydrogen is pumped from the source to the first heat exchanger and theresult pressurized gaseous hydrogen is used to refill the buffercontainers.

The invention provides several advantages.

The vaporizer used in the invention need not be very tall. Indeed, itcan remain under 10′ in height. This is important because, in urbanlocations, the presence of overhead power lines, telephone lines, ortrees restricts the vertical space that may be taken up by conventionalambient air vaporizers. In contrast to the vaporizer used in theinvention, conventional ambient air vaporizers often exceed 10′ inheight.

In comparison to ambient air vaporizers, the vaporizer used in theinvention allows more precise control of the outlet temperature of thehydrogen at the dispenser that is necessary for meeting stringenttemperature control profiles required by many hydrogen fillingprotocols, such as the SAE J2601. Because conventional ambient airvaporizers exchange heat with liquefied cryogenic gases in a largelypassive manner, the temperature of the vaporized cryogen will highlydepend upon the ambient temperature. In the invention, the temperatureof the heat transfer fluid exiting the second heat exchanger may beprecisely controlled through precise control of the blower speed or theelectrical power supplied to a heater. This in turn allows more precisecontrol of the vaporized hydrogen exiting the first heat exchanger afterexchanging heat with the temperature-controlled heat transfer fluid.

While the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives,modifications, and variations will be apparent to those skilled in theart in light of the foregoing description. Accordingly, it is intendedto embrace all such alternatives, modifications, and variations as fallwithin the spirit and broad scope of the appended claims. The presentinvention may suitably comprise, consist or consist essentially of theelements disclosed and may be practiced in the absence of an element notdisclosed. Furthermore, if there is language referring to order, such asfirst and second, it should be understood in an exemplary sense and notin a limiting sense. For example, it can be recognized by those skilledin the art that certain steps can be combined into a single step.

The singular forms “a”, “an” and “the” include plural referents, unlessthe context clearly dictates otherwise.

“Comprising” in a claim is an open transitional term which means thesubsequently identified claim elements are a nonexclusive listing i.e.anything else may be additionally included and remain within the scopeof “comprising.” “Comprising” is defined herein as necessarilyencompassing the more limited transitional terms “consisting essentiallyof” and “consisting of”; “comprising” may therefore be replaced by“consisting essentially of” or “consisting of” and remain within theexpressly defined scope of “comprising”.

“Providing” in a claim is defined to mean furnishing, supplying, makingavailable, or preparing something. The step may be performed by anyactor in the absence of express language in the claim to the contrary.

Optional or optionally means that the subsequently described event orcircumstances may or may not occur. The description includes instanceswhere the event or circumstance occurs and instances where it does notoccur.

Ranges may be expressed herein as from about one particular value,and/or to about another particular value. When such a range isexpressed, it is to be understood that another embodiment is from theone particular value and/or to the other particular value, along withall combinations within said range.

All references identified herein are each hereby incorporated byreference into this application in their entireties, as well as for thespecific information for which each is cited.

What is claimed is:
 1. A method of filling a tank of a fuel cellelectric vehicle with pressurized hydrogen, comprising the steps of:feeding liquid hydrogen from a source of liquid hydrogen to a fillingcircuit whose downstream end is removably connected to the tank, thefilling circuit having a first heat exchanger is disposed therein, thefirst heat exchanger having a liquid hydrogen inlet, a gaseous hydrogenoutlet, a heat transfer fluid inlet, and a heat transfer fluid outlet;pumping a heat transfer fluid with a heat transfer pump through a heattransfer circuit looping from and to the first heat exchanger, the heattransfer circuit comprising, in flow order from the heat transfer fluidoutlet to the heat transfer fluid inlet, a second heat exchanger and theheat transfer fluid pump; exchanging heat, with the first heatexchanger, between the heat transfer fluid flowing through the heattransfer fluid circuit and the liquid hydrogen fed to the fillingcircuit from the source, thereby vaporizing the fed liquid hydrogen andcooling the heat transfer fluid, wherein the fed liquid hydrogen insidethe first heat exchanger is surrounded by the heat transfer fluid;heating, with the second heat exchanger, the cooled heat transfer fluidreceived from the first heat exchanger; and filling a tank of ahydrogen-fueled vehicle with pressurized, gaseous hydrogen from thedownstream end of the filling circuit.
 2. The method of claim 1, furthercomprising the step of pumping the liquid hydrogen, with a liquidhydrogen pump, from the source into the filling circuit.
 3. The methodof claim 1, further comprising the steps of: measuring a pressure of thepressurized, gaseous hydrogen in the filling circuit downstream of thefirst heat exchanger with a pressure sensor; and controlling a pressureof the pressurized, gaseous hydrogen with a pressure control valve basedupon the pressure of the pressurized, gaseous hydrogen measured by thepressure sensor.
 4. The method of claim 1, wherein: the heat transfercircuit further comprises a primary line, a bypass line, a three-wayflow control valve, a temperature sensor, and a downstream line in flowcommunication between the three-way flow control valve and the heattransfer fluid pump; the primary line extends in flow communicationbetween the first heat exchanger and the three-way flow control valve;the bypass line branches off of the primary line and is in upstream flowcommunication with the three-way flow control valve; the second heatexchanger is disposed in the primary line; the three-way flow controlvalve controls flows of warmed heat transfer fluid from the primary lineand non-warmed heat transfer fluid from the bypass line, combines theflow of the warmed heat transfer fluid from the primary line and theflow of the non-warmed heat transfer fluid from the bypass line, anddirects the combined flow of heat transfer fluid to the heat transferpump; the temperature sensor is disposed in the heat transfer circuit inbetween the three-way flow control valve and the first heat exchanger;and the three-way control valve controls a temperature of the heattransfer fluid in between the three-way control valve and the first heatexchanger by adjusting a ratio of the flow rate of the warmed heattransfer fluid to the flow rate of the non-warmed heat transfer fluid inthe combined flow of heat transfer fluid.
 5. The method of claim 1,wherein the heat transfer fluid circuit further comprises a blower thatis adapted and configured to blow ambient air at the second heatexchanger so as to warm the heat transfer fluid with the heat of theblown ambient air.
 6. The method of claim 1, wherein the second heatexchanger is an electric heater adapted and configured to warm the heattransfer fluid.
 7. The method of claim 1, further comprising two or morebuffer containers, a leg branching off of the filling circuit downstreamof the first heat exchanger that is adapted and configured to direct thepressurized, gaseous hydrogen from the first heat exchanger to the twoor more buffer containers, a set of valves, and a pressure controlvalve, the set of valves being adapted and configured to allow thepressurized, gaseous hydrogen to flow through the leg and into one ofthe buffer containers but not into other of the buffer containers andallow the pressurized, gaseous hydrogen to flow from one of the buffercontainers through the leg and to the downstream end of the fillingcircuit, the pressure control valve being adapted and configured tocontrol a pressure of the pressurized, gaseous hydrogen flowing out ofthe downstream end of the filling circuit based upon a pressure sensedby a pressure sensor disposed in the filling circuit between the leg andthe downstream end of the filling circuit.
 8. The method of claim 1,wherein the filling circuit further comprises a primary line in fluidcommunication between the upstream and downstream ends of the fillingcircuit, a bypass line that branches off from the primary line andrecombines with the primary line downstream of the first heat exchanger,a flow control valve disposed in the primary line, a flow control valvedisposed in the bypass line, and a temperature sensor disposed in thefilling circuit downstream of a point where the bypass line recombineswith the primary line and upstream of the downstream end of the fillingcircuit, the first heat exchanger being disposed in the primary line,the flow control valve disposed in the primary line being adapted andconfigured to control a flow of vaporized hydrogen flowing through theprimary line, the flow control valve disposed in the bypass lines beingadapted and configured to control a flow of liquid hydrogen flowingthrough the bypass line, the flow control valves controlling the flowsof vaporized hydrogen and liquid hydrogen to in turn control atemperature of the pressurized, gaseous hydrogen for filling the tankthat is based upon a temperature sensed by the temperature sensor. 9.The method of claim 1, wherein the heat transfer circuit furthercomprises a heat transfer reservoir in fluid communication between thesecond heat exchanger and the heat transfer pump, the heat transferreservoir being adapted and configured to contain a volume of the heattransfer fluid.
 10. A method of filling a tank of a fuel cell electricvehicle with pressurized hydrogen, comprising the steps of: feedingliquid hydrogen from a source of liquid hydrogen to a filling circuitwhose downstream end is removably connected to a tank of ahydrogen-fueled vehicle, the filling circuit having a first heatexchanger is disposed therein, the first heat exchanger having a liquidhydrogen inlet, a gaseous hydrogen outlet, a heat transfer fluid inlet,and a heat transfer fluid outlet; pumping a heat transfer fluid with aheat transfer pump through a heat transfer circuit looping from and tothe first heat exchanger, the heat transfer circuit comprising, in floworder from the heat transfer fluid outlet to the heat transfer fluidinlet, a second heat exchanger and the heat transfer fluid pump;exchanging heat, with the first heat exchanger, between the heattransfer fluid flowing through the heat transfer fluid circuit and theliquid hydrogen fed to the filling circuit from the source, therebyvaporizing the fed liquid hydrogen and cooling the heat transfer fluid,wherein the fed liquid hydrogen inside the first heat exchanger issurrounded by the heat transfer fluid; heating, with the second heatexchanger, the cooled heat transfer fluid received from the first heatexchanger; directing the vaporized liquid hydrogen into one or morebuffer container; and filling a tank of a hydrogen-fueled vehicle withpressurized, gaseous hydrogen from the one or more buffer containers.11. The method of claim 10, further comprising the step of pumping theliquid hydrogen, with a liquid hydrogen pump, from the source into thefilling circuit.
 12. The method of claim 10, further comprising thesteps of: measuring a pressure of the pressurized, gaseous hydrogen inthe filling circuit downstream of the first heat exchanger with apressure sensor; and controlling a pressure of the pressurized, gaseoushydrogen with a pressure control valve based upon the pressure of thepressurized, gaseous hydrogen measured by the pressure sensor.
 13. Themethod of claim 10, wherein: the heat transfer circuit further comprisesa primary line, a bypass line, a three-way flow control valve, atemperature sensor, and a downstream line in flow communication betweenthe three-way flow control valve and the heat transfer fluid pump; theprimary line extends in flow communication between the first heatexchanger and the three-way flow control valve; the bypass line branchesoff of the primary line and is in upstream flow communication with thethree-way flow control valve; the second heat exchanger is disposed inthe primary line; the three-way flow control valve controls flows ofwarmed heat transfer fluid from the primary line and non-warmed heattransfer fluid from the bypass line, combines the flow of the warmedheat transfer fluid from the primary line and the flow of the non-warmedheat transfer fluid from the bypass line, and directs the combined flowof heat transfer fluid to the heat transfer pump; the temperature sensoris disposed in the heat transfer circuit in between the three-way flowcontrol valve and the first heat exchanger; and the three-way controlvalve controls a temperature of the heat transfer fluid in between thethree-way control valve and the first heat exchanger by adjusting aratio of the flow rate of the warmed heat transfer fluid to the flowrate of the non-warmed heat transfer fluid in the combined flow of heattransfer fluid.
 14. The method of claim 10, wherein the heat transferfluid circuit further comprises a blower that is adapted and configuredto blow ambient air at the second heat exchanger so as to warm the heattransfer fluid with the heat of the blown ambient air.
 15. The method ofclaim 10, wherein the second heat exchanger is an electric heateradapted and configured to warm the heat transfer fluid.
 16. The methodof claim 10, wherein: the one or more buffer containers comprises two ormore buffer containers, and: a leg branches off of the filling circuitdownstream of the first heat exchanger that is adapted and configured todirect the pressurized, gaseous hydrogen from the first heat exchangerto the one or more buffer containers; a set of valves is adapted andconfigured to allow the pressurized, gaseous hydrogen to flow throughthe leg and into one of the two or more buffer containers but not intoothers of the two or more buffer containers and allow the pressurized,gaseous hydrogen to flow from one of the two or more buffer containersthrough the leg and to the downstream end of the filling circuit; andcontrolling, using the pressure control valve, a pressure of thepressurized, gaseous hydrogen flowing out of the downstream end of thefilling circuit based upon a pressure sensed by a pressure sensordisposed in the filling circuit between the leg and the downstream endof the filling circuit.
 17. The method of claim 10, wherein the fillingcircuit further comprises a primary line in fluid communication betweenthe upstream and downstream ends of the filling circuit, a bypass linethat branches off from the primary line and recombines with the primaryline downstream of the first heat exchanger, a flow control valvedisposed in the primary line, a flow control valve disposed in thebypass line, and a temperature sensor disposed in the filling circuitdownstream of a point where the bypass line recombines with the primaryline and upstream of the downstream end of the filling circuit, thefirst heat exchanger being disposed in the primary line, the flowcontrol valve disposed in the primary line being adapted and configuredto control a flow of vaporized hydrogen flowing through the primaryline, the flow control valve disposed in the bypass lines being adaptedand configured to control a flow of liquid hydrogen flowing through thebypass line, the flow control valves controlling the flows of vaporizedhydrogen and liquid hydrogen to in turn control a temperature of thepressurized, gaseous hydrogen for filling the tank that is based upon atemperature sensed by the temperature sensor.
 18. The method of claim10, wherein the heat transfer circuit further comprises a heat transferreservoir in fluid communication between the second heat exchanger andthe heat transfer pump, the heat transfer reservoir being adapted andconfigured to contain a volume of the heat transfer fluid.